Cystic fibrosis (CF) is the most common lethal hereditary disease in the United States and the leading causes of chronic obstructive pulmonary disease in children. Because of the multitude of secondary complications in patients with the disorder, studies on the pathogenesis of CF are almost exclusively limited to in vitro systems. The conference proposed in the application is the second to be held on the use of tissue culture in the study of cystic fibrosis. The first such meeting, held in 1971, was attended by 33 authorities in the field and produced a report summarizing the state of the art and citing desirable further directions for research in this area. Since then, a number of developments have occurred pertaining to both basic methodology and observations on CF cells studied in vitro. In particular, fundamental properties of skin fibroblasts have now been carefully examined and new approaches described for the study of tracheal-bronchial epithelium. There are a number of conflicting experimental observations on CF cells, however, as well as major differences in techniques used to grow and study fibroblasts. Because of unsolved problems surrounding the pathogenesis of cystic fibrosis and the need to pursue such studies in vitro, the tissue culture approach will continue to attract investigators from many disciplines who are concerned with CF and related diseases. It is timely to gather these scientists together for joint consideration of the new developments. Major areas to be explored by the participants are: 1) experimental findings on the growth, morphology, and biochemistry of skin fibroblasts from CF patients, and 2) the use of tracheal-bronchial epithelium in the investigation of mucous glycoprotein biosynthesis.